Evaluation of the Structure and Dispersion in Polymer-Layered Silicate Nanocomposites

Abstract

Polymer-layered silicate nanocomposites have drawn a great interest in polymer science these past years. Understanding of the complex mechanism of dispersion and exfoliation of the clay tactoids may allow us to better control the final morphology and the homogeneity of clay nanocomposites and thus their macroscopic properties. The first step we propose in this study consists of a multiscale approach of the exfoliation state of the extruded polypropylene/montmorillonite nanocomposite. We used three extruders designs: a single-screw extruder, a twin-screw extruder, and an optimized-screw extruder with adapted shear. The rheological analysis, the WAXS diffractograms, and the TEM micrographs all show different nanocomposite morphologies. A statistical TEM image analysis methodology was developed to evaluate the different particle parameters (thickness, length, aspect ratio, interparticle distance). The results obtained show a correlation between the size of the tactoids and the shear intensity.

Crossed characterisation of polymer-layered silicate (PLS) nanocomposite morphology: TEM, X-ray diffraction, rheology and solid-state nuclear magnetic resonance measurements

“…However image analysis procedure can be used to quantify the dispersion from TEM pictures. Vermogen et al 13 deduce different parameters which give detailed information and allow a very fine description of the microstructure (Figure 2). The average thicknesses, lengths, and aspect ratios of each class of tactoids could be measured as well as their relative proportions and the average distances between two adjacent tactoids.…”

Effect of an Organo-Modified Montmorillonite on the Barrier Properties of PET Nanocomposites Using a Polyester Ionomer as a Compatibilizing Agent

“…These nanocomposites show improved mechanical and barrier properties compared to the corresponding neat polymer matrix and conventional composites due to the nano-scale reinforcement and the tortuous diffusion path caused by the high aspect ratio of aluminosilicate layers [1][2][3][4][5] . In order to maximize these benefits it is necessary to achieve a high level of organoclay exfoliation, uniform distribution and appropriate orientation of clay platelets [6][7][8][9] . Among various processes, the following two are considered as being commercially attractive for preparing layered silicate based polymer nanocomposites: in situ polymerization and melt compounding 10,11 .…”

Fabrication, Structure and Properties of Epoxy/Metal Nanocomposites

“…[2] Two methods have been developed to-date for the fabrication of polymer/metal nanocomposites, including: (i) the in situ method involves mixing metal precursors with hydrophilic polymers, i.e., poly(ethylene glycol) and poly(vinyl alcohol), followed by thermal or photochemical reduction, [3][4][5][6][7][8] and (ii) the transfer method involves the preparation of nanoparticles and the subsequent solution mixing with polymers. [9][10][11][12][13][14] Both methods are not satisfactory in terms of engineering applications, because (i) the in situ method requests hydrophilic polymer matrixes, and this seriously limits its application, because the majority of composites require stability against moisture; and (ii) the transfer method requires solvents and a large amount of surfactants for the surface modification of nanoparticles to prevent agglomeration and yields low particle concentrations in the final products (maximum 4 wt.-%). The in situ method was recently used to produce polyolefin/metal oxide nanocomposite by a complicated method.…”